The geomagnetic field was quiet on January 31. Solar wind speed at SOHO ranged between 376 and 466 km/sec. The high latitude magnetometer at Andenes recorded quiet to active levels. The above 10 MeV proton flux was at 1 pfu at the end of the day, slowly decreasing. A weak solar wind shock was observed at 05:18 UT on February 1 at DSCOVR, likely the arrival of the January 29 CME.
Solar flux density measured at 20h UT on 2.8 GHz was 136.2 - decreasing 10.8 over the previous solar rotation. (Centered 1 year average SF at 1 AU - 183 days ago: 157.02. In comparison SC24 peaked on June 28, 2014 at 145.50. Current SC25 peak: 158.71 on June 27, 2023). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.6). Three hour interval K indices: 22111111 (planetary), 22112321 (Boulder), 33110243 (Andenes).
The background x-ray flux is at the class B6 level (GOES 16).
At the time of counting spots (see image time), spots were observed in 13 active regions using 2K resolution (SN: 269) and in 12 active regions using 1K resolution (SN: 183) SDO/HMI images.
Region 13565 [N05E26] developed slowly and may
be capable of minor M class flaring. C1 flares: C1.1 @ 04:17, C1.5 @ 20:52
UT
Region 13566 [S12W74] decayed slowly and quietly.
Region 13567 [N19E48] decayed in the trailing spot section as the main penumbral area fragmented.
Slow development was observed in the intermediate and leading spot section. M class flares are possible.
C1 flares: C1.3 @ 04:34, C1.3 @ 05:11, C1.6 @ 09:44, C1.0 @ 10:17, C1.4 @
12:18, C1.1 @ 16:47, C1.2 @ 20:29 UT
Region 13568 [S09W49] was quiet and stable.
New region 13569 [S12W10] emerged on January 28 and was numbered by
SWPC 3 days later.
Spotted regions not observed (or interpreted
differently) by SWPC/USAF:
S9366 [N21E04] was mostly quiet and stable. C1 flares: C1.5 @ 21:25
UT
S9371 [S08E06] decayed slowly and was mostly quiet. C1 flares: C1.7 @
13:22 UT
S9383 [S16W30] reemerged with tiny spots.
S9385 [N19W37] was quiet and stable.
S9388 [S03E62] was quiet and stable.
New region S9389 [S12E37] emerged with tiny spots.
New region S9390 [S17E77] rotated into view with a mature large spot.
New region S9391 [S36E01] emerged with a tiny spot.
AR S9346 behind the northwest limb produced a C1.9 flare at 05:26 and a C1.3 flare at 11:08 UT
C2+ flares:
| Magnitude | Peak time (UT) | Location | Source | Recorded by | Comment |
| C3.2 | 06:31 | N04E36 | 13565 | GOES16 | |
| C4.5 | 08:29 | N19E56 | 13567 | GOES16 | |
| C2.4 | 13:45 | N04E31 | 13565 | GOES16 |
January 30-31: No obviously Earth directed CMEs were observed.
January 29: A partial halo CME was observed after the M6.8 flare in
AR 13559 early in the day. While Earth is not in the path of the major part
of the ejecta, there is a chance of a shock arrival on January 31.
[Coronal hole history (since October 2002)]
[Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago]
A positive polarity southern hemisphere coronal hole (CH1201) could become Earth facing on February 1-2.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over upper middle and high latitudes is poor. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet to unsettled on February 1 due weak CME effects. A quiet geomagnetic field is likely on February 2-3.
| Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
1) Effects from a coronal hole
could reach Earth within the next 5 days. When the high speed
stream has arrived the color changes to green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48 hours.
Green: 0-30% probability, Yellow: 30-70% probability, Red: 70-100% probability.
(Click on image for 2K resolution).
4K resolution.
Compare to the previous
day's image. 0.5K image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue is positive.
Data for all officially numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC, all other regions are numbered sequentially as they emerge using the STAR spot number. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers. SWPC data considered to be not sufficiently precise (location, area, classification) are colored red.
| Active region | SWPC date numbered STAR detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with magnetic polarity overlays |
Comment | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| SWPC/ USAF |
Magnetic (SDO) |
SWPC | STAR | Current | Previous | ||||||
| 2K | 1K | ||||||||||
| S9346 | 2024.01.19 | N28W89 | |||||||||
| S9364 | 2024.01.24 | S10W58 | |||||||||
| S9366 | 2024.01.25 | 14 | 3 | N21E04 | 0020 | BXO |
 |
 |
|||
| S9367 | 2024.01.25 | N31W30 | |||||||||
| S9368 | 2024.01.25 | S26W50 | |||||||||
| 13563 | 2024.01.26 2024.01.26 |
S05W39 |
 |
location: S07W33 | |||||||
| S9370 | 2024.01.26 | N15W25 | |||||||||
| S9371 | 2024.01.26 | 9 | S08E06 | 0025 | BXO |
 |
 |
||||
| S9375 | 2024.01.26 | S21W25 | |||||||||
| 13568 | 2024.01.27 2024.01.30 |
4 | 9 | 4 | S10W51 | 0030 | BXO | DRO |
 |
 |
location: S09W49 |
| 13566 | 2024.01.27 2024.01.30 |
3 | 5 | 4 | S13W75 | 0080 | DAO | CRO |
 |
 |
area: 0025 location: S12W74 |
| S9379 | 2024.01.27 | N31W31 | |||||||||
| 13565 | 2024.01.27 2024.01.28 |
5 | 29 | 13 | N07E23 | 0050 | DAO | DRI |
 |
 |
beta-gamma location: N06E26 area: 0090 |
| 13564 | 2024.01.28 | S09E14 | |||||||||
| 13567 | 2024.01.28 2024.01.30 |
12 | 44 | 23 | N19E54 | 0220 | DAI | DAI |
 |
 |
beta-gamma location: N19E48 area: 0480 |
| 13569 | 2024.01.28 | 1 | 4 | 3 | S12W10 | 0010 | AXX | CRO |
 |
 |
area: 0015 |
| S9383 | 2024.01.29 | 4 | 2 | S16W30 | 0008 | BXO |
 |
||||
| S9384 | 2024.01.29 | S35W10 | |||||||||
| S9385 | 2024.01.30 | 4 | 3 | N19W37 | 0012 | BXO |
 |
 |
|||
| S9386 | 2024.01.30 | N05W36 |
 |
||||||||
| S9387 | 2024.01.30 | N11W26 |
 |
||||||||
| S9388 | 2024.01.30 | 8 | 3 | S03E62 | 0030 | DRO |
 |
 |
|||
| S9389 | 2024.01.31 | 7 | 3 | S12E37 | 0013 | CRO |
 |
||||
| S9390 | 2024.01.31 | 1 | 1 | S17E77 | 0250 | HHX |
 |
||||
| S9391 | 2024.01.31 | 1 | 1 | S36E01 | 0004 | AXX |
 |
||||
| Total spot count: | 25 | 139 | 63 | ||||||||
| Sunspot number: | 75 | 269 | 183 | (total spot count + 10 * number of spotted regions) | |||||||
| Weighted SN: | 40 | 172 | 96 | (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10) | |||||||
| Relative sunspot number (Wolf number): | 83 | 148 | 146 | ||||||||
| Month | Average solar flux | International sunspot number (WDC-SILSO) |
Smoothed sunspot number (4) | Average ap (3) |
|
|---|---|---|---|---|---|
| Measured | 1 AU | ||||
| 2014.02 | 170.3 (cycle peak) |
166.3 | 146.1 (SC24 peak) | 110.5 | 10.70 |
| 2014.04 | 143.9 | 144.8 | 112.5 | 116.4 (SC24 solar max) | 7.88 |
| 2017.09 | 91.3 | 92.3 | 43.6 | 18.2 (-1.3) | 18.22 (SC24 peak) |
| 2019.11 | 70.2 | 68.7 | 0.5 | 2.0 (-0.6) (Solar minimum using 365d smoothing: November 17, 2019) |
4.19 |
| 2019.12 | 70.8 | 68.6 | 1.6 | 1.8 (-0.2) (ISN 13 months smoothed solar minimum) |
3.22 |
| 2022.05 | 133.8 | 136.8 | 96.5 | 77.4 (+4.4) | 7.48 |
| 2022.06 | 116.1 | 119.8 | 70.3 | 81.1 (+3.7) | 8.20 |
| 2022.07 | 125.4 | 129.5 | 91.4 | 86.7 (+5.6) | 9.51 |
| 2022.08 | 114.2 | 117.1 | 74.6 | 92.6 (+5.9) | 10.92 |
| 2022.09 | 135.1 | 136.5 | 96.0 | 96.5 (+3.9) | 12.18 |
| 2022.10 | 133.5 | 132.7 | 95.5 | 98.9 (+2.4) | 11.16 |
| 2022.11 | 123.4 | 120.7 | 80.5 | 101.2 (+2.3) | 9.33 |
| 2022.12 | 147.9 | 143.4 | 112.8 | 106.7 (+5.5) | 10.99 |
| 2023.01 | 182.4 | 176.6 | 144.4 | 113.3 (+6.6) | 8.73 |
| 2023.02 | 167.2 | 163.2 | 111.3 | 117.8 (+3.5) | 14.48 (current SC25 peak) |
| 2023.03 | 157.2 | 155.6 | 123.3 | 121.0 (+3.2) | 14.42 |
| 2023.04 | 145.4 | 146.4 | 97.6 | 122.7 (+1.7) | 13.40 |
| 2023.05 | 155.6 | 159.2 | 137.4 | 123.9 (+1.2) | 10.67 |
| 2023.06 | 161.7 | 166.8 | 160.5 | 125.0 (+1.1) (SC25 solar max candidate) |
8.95 |
| 2023.07 | 176.4 | 182.2 | 160.0 | (124.6 projected, -0.4) | 8.15 |
| 2023.08 | 153.7 | 157.6 | 114.8 | (124.1 projected, -0.5) | 7.19 |
| 2023.09 | 154.4 | 156.0 | 134.2 | (123.8 projected, -0.3) | 14.26 |
| 2023.10 | 142.8 | 141.9 | 99.4 | (124.6 projected, +0.8) | 8.16 |
| 2023.11 | 153.5 | 150.2 | 105.4 | (124.6 projected, +0.0) | 12.20 |
| 2023.12 | 151.1 | 146.4 | 114.2 | (121.2 projected, -3.4) | 9.60 |
| 2024.01 | 164.5 | 159.3 | 119.4 (2A) / 123.3 (2B) / 161.4 (2C) | (117.9 projected, -3.3) | 5.6 |
| 2024.02 | (1) | (117.1 projected, -0.8) | () | ||
| 2024.03 | (116.6 projected, -0.5) | ||||
| 2024.04 | (116.6 projected, +0.0) | ||||
| 2024.05 | (117.0 projected, -0.8) | ||||
| 2024.06 | (114.9 projected, -2.1) | ||||
1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz
and any corrections applied to that measurement.
2A) Current impact on the monthly sunspot number based on the Boulder (NOAA/SWPC) sunspot number (accumulated daily sunspots / month days).
2B) Boulder SN current month average to date.
2C) STAR SDO 1K Wolf number 30 day average.
3) Running average based on the quicklook and definitive Potsdam WDC ap indices. Values in red
are based on the definitive international
GFZ Potsdam WDC ap indices.
4) Source: WDC-SILSO, Royal Observatory
Of Belgium, Brussels
The relatively low solar activity during the last months of 2023 significantly increased the possibility that solar cycle 25 has already peaked. Whether the first peak in June 2023 will be the actual solar max will not be known for some time. Due to the relatively high solar activity early in 2023 it is unlikely there will be another solar max candidate, if at all, until at least May 2024. Both the northern and southern polar fields, as well as the averaged total field, have already reversed polarities.
--------------------------------------------------------------------------------------
This report has been prepared by Jan Alvestad. It is based on the analysis of data from whatever sources are available at the time the report is prepared. All time references are to Universal Time. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
